As already stated, even if the witnesses decided to remove an account (which they never have, with the exception of when Hive was created in order to remove Justin Sun's power) - anyone could fork the blockchain prior to the account being removed, so nothing would be lost, provided people step up to manage the system that they personally value more than Hive.
RE: Web 3.0 & The Hive Blockchain Fix Big Tech Censorship! Be Part Of The Freedom Revolution On Hive!